巻号一覧
62 巻, 3 号
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2高館高アルミナ玄武岩阿部 智彦, 青木 謙一郎1969 年 62 巻 3 号 p. 177-190
発行日: 1969/09/05
公開日: 2008/08/07
ジャーナル フリーThe Neogene volcanic activity of the Sendai area can be divided geologically into the following three groups: lower Miocene series (Takadate volcanics), upper Miocene series (Mitaki volcanics), and Quaternary volcanoes. The Takadate volcanics are composed of highalumina basalt series basalt and andesite, while lower half of the Mitaki volcanics is composed of high-alumina basalt series basalt and andesite and upper half is composed of tholeiite series basalt and andesite. These activities were accompanied calc-alkaline series. The chemical analyses of 15 representative rocks from the Takadate volcanics and lower part of the Mitaki volcanics, including 14 new analyses, are given in Table 2. There are conspiquous difference between the fractionation trends of both high-alumina basalt series and tholeiite series; the former shows moderate iron enrichment at the middle stage of crystallization, whereas the latter shows strong iron concentration (Aoki, 1967).
It is noticed that the rock series of the Mitaki volcanics were changed abruptly from high-alumina basalt series to tholeiite series during the succesive eruption. From petrological study, it is concluded that when crossing the northeastern Japan from the Pacific to the Japan Sea side, tholeiite, high-alumina basalt, and alkali basalt provinces is distinguished for the upper Miocene to Recent volcanic activities. However, there is no tholeiite province in the lower to upper Miocene volcanic activities.抄録全体を表示PDF形式でダウンロード (726K) -
石坂 恭一1969 年 62 巻 3 号 p. 191-197
発行日: 1969/09/05
公開日: 2008/08/07
ジャーナル フリーU-Th-Pb ages of three zircons of granitic and metamorphic rocks from Ryoke metamorphic zone in the Kinki district have been determined. Two zircons from granitic rocks yielded Pb206/U238 age of approximately 90 m. y. which is consistent with the results obtained by Rb-Sr method on mica samples of this metamorphic terrain, suggesting the intrusion of the granitic rocks and metamorphic may have taken place about 90 m. y. ago. Detrital zircon of metamorphosed Paleozoic sedimentary rock yielded quite discordant U-Pb age, Pb207/Pb206 age being as old as 1792 m. y.. This result may indicate the presence of acidic crystalline rocks of Precambrian age near the so-called Permo-Carboniferous Paleozoic rock region, probably in the Japan Sea.抄録全体を表示PDF形式でダウンロード (1082K) -
北見国紋別郡白滝地域の玻璃質岩佐藤 文男, 白幡 浩志1969 年 62 巻 3 号 p. 198-208
発行日: 1969/09/05
公開日: 2008/08/07
ジャーナル フリーThe authors have investigated the petrochemical characters of holohyaline rocks from Shirataki district, Hokkaido, and the following results were obtained.
(1) X-ray studies on the spherulite showed that they are mainly composed of cristobalite and anorthoclase (and albite).
(2) Fifteen specimens of holohyaline rocks were chemically analyzed, and it is found that they are generally poor in CaO, richer in alkalines, especially in K2O and range from 68.52 to 76.72 per cent in silica content. On the other hand, spherulite is richer in CaO and its alkali content is distinct, in Na2O.
(3) The diagramatic reprensentation of the system Na2O+K2O-SiO2 shows that most of the holohyaline rocks except spherulite have an intermadiate character between the tholeiitic rock suite of the Nasu-Fuji volcanic zone and alkalic rock suite of Circum Japan Sea province.
(4) The analytical compositions of obsidian, perlite and pitchstone group close to the minimum in the system NaAlSi3O8-KAlSi3O8-SiO2 (Tuttle and Bowen, 1958), and obsidian and perlite correspond closely with the minimum at 500kg/cm2 and/or 1000kg/cm2 water vapour pressure.抄録全体を表示PDF形式でダウンロード (649K) -
土方 研一, 大沼 晃助1969 年 62 巻 3 号 p. 209-218
発行日: 1969/09/05
公開日: 2008/08/07
ジャーナル フリー空気中におけるCaMgSi2O6-CaFe3+AlSiO6(以下Fpと略す)系相平衡状態図を決定した。その結果この系はDi52.5・Fp47.5に1265°Cの最低点を有する単斜輝石としての完全な固溶体をつくることがわかった。またこれら単斜輝石固溶体の格子定数および屈折率の変化はFpの増加に対して直線的関係を有している。
トウ輝石成分の多い側(Di6-Di54)は二成分系的であるがFp成分の多い側(Di54-Fp100)ではこの系がFe-O-CaO-mgO-Al2O3-SiO2系すなわち6成分系の一部分であるためにより複雑である。Fpを46mol%以上含む組成の単斜輝石固溶体はマグネタイト固溶体+液+ガス,マグネタイト固溶体+X(未知相)+ガスあるいはX+液+ガスに分解溶融する。抄録全体を表示PDF形式でダウンロード (402K) -
鷹村 権1969 年 62 巻 3 号 p. 219-221
発行日: 1969/09/05
公開日: 2008/08/07
ジャーナル フリーPDF形式でダウンロード (99K)
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